1. Field of the Invention
This invention relates generally to an apparatus for a watercraft propelled by a water jet. In particular, the invention pertains to a device for cutting weeds and other debris contained in water inducted into the propulsion system.
2. Description of the Prior Art
A jet-boat is a boat propelled by a jet of water ejected from the back of the craft. Unlike a powerboat or motorboat that uses a propeller in the water behind the boat, a jet-boat draws the water from under the boat into a pump-jet inside the boat, then expels it through a nozzle at the stern.
Jet-boats are highly maneuverable, and can be reversed and brought to a stop within a short distance from full speed.
A conventional screw impeller accelerates a large volume of water by a small amount, similar to the way an airplane's propeller accelerates a large volume of air by a small amount. By contrast, an aircraft's jet engine accelerates a small volume of air by a large amount. In a jet-boat, pumping a small volume of water, accelerating it by a large amount, and expelling the water above the water line delivers thrust that propels the craft. The acceleration of the water is achieved by using an impeller.
Jet-boats normally plane across the water surface, with only the rear portion of the hull displacing any water. With the majority of the hull clear of the water, drag is reduced and maneuverability is enhanced. For stability, a jet-boat has a very shallow-angled hull. At speed, jet-boats can be safely operated in less than 12 inches (30 cm) of water.
Jet-boats are frequently operated in shallow fresh water where waterweeds flourish. These weeds grow in long strands that are often drawn into the water induction and propulsion system can become entangled with the impeller blades, shafts and ducting, and can clog the propulsion system. In extreme cases, the induction and propulsion system can become so filled with weeds and debris that the engine is stalled or water cannot be pumped at a rate that satisfactorily propels the craft. When this occurs, the craft must be removed from the water and the weeds removed manually.
There is a need in the industry for an effective, safe and reliable technique for cutting waterweeds and debris inducted into the propulsion system into lengths that are short enough to flow through the intake duct and impeller and out the nozzle without collecting there or impeding water flow through the propulsion system.